Electric alarm.



W. C. NEAHR.

ELECTRIC ALARM.

APPLICATION FILED NOV. 27, 1914.

1 1 'K'Y'j, Patented June 20, 1916.

2 SHEETS--SHEET y I 0 /1\ WITNESSES: Z I 3 IN VEN TOR.

M W C. A/eah/i' THE cpLuMmA PLANonRAPu co., wAsn lNa'roN, n. c.

W. C. NEAHR.

ELECTRIC ALARM.

APPLICATION FILED NOV. 21. 1914.

Patented June 20, 1916.

m i J H m m i M 2 SHEETS-SHEET 2- .7WITNESSES: k4 I a? I VE TOR. .C. fifafrr' TTnR NFL rm: COLUMBIA ILANOGRAPH co., WASHlNG'rbI-J, D. C.

unrrnn sraarns PATENT onrieia WILL C. NEAI-IR, OF DENVER, COLORADO,ASSIGNOR TO THE PROTECTIVE SIGNAL MANUFACTURING COMPANY, A CORPORATIONOF COLORADO.

ELECTRIC ALARM.

Specification of Letters Patent.

Patented June so, rare.

which in cooperation with the armature of the electro-magnet breaks themagnet circuit at a determinate point in the movement of the armaturetoward the magnet coils.

Other objects ofmy invention reside in the provision of novel means tocoopeia tivcly associate the armature with the hammer of the alarm, andin providing an adjustable and resilient abutment by which the frequencyof the hammer-strokes, and in consequence that of the vibratingmovementof the armature, may be varied at will, and which renders themovements of the hammer equable and mitigates the impact of the contactmembers included in the circuit controlling device.

A further object of my invention is to provide a housing for theoperating mechanism of the alarm which adequately protects the same fromdust and moisture without interfering with the movements of the hammerwith relation to an eXteriorly disposed gong, and still further objectsreside in minor details of construction, all of which will fully appearin the following description of my invention with relation to theaccompanying drawings in the various views of which like parts aresimilarly designated, and in which, I

Figure 1 represents a face view of the electric alarm in which thegreater portions of the gong and the cover of the housing havebeenomitted to show the operating mechanism within the housing, Fig. 2, asection taken along the line 22, Fig. 1, looking in the direction of thearrow drawn across the line, Fig. 3, a face view of the alarm housingwithout the gong, drawn to a reduced scale, Fig. 4, an enlargedelevation of the circuit-controlling device included in the operatingmechanism, Fig. 5, a section along the line 55, Fig. 4, and Fig. 6,. anenlarged section taken along the line 6-6, Fig. 1;.

Referring more specifically to the drawings, the reference character 2designates the housing of the alarm which comprises a body portioncomposed of a back plate 3 and a therewith integral, cylindrical sidewall 4, and a cover 5.

The housing has in the plane of its back plate, diametrically oppositelugs 6 for its attachment against an upright surface of a suitablesupport, and the cover has a circumferential flange which is formed tofit snugly around the outer edge of the wall 4 against which the coveris placed, to close the interior of the housing against dirt andmoisture.

Bolts 7 extending through axially alined apertures in the cover and theback plate of the housing, serve to securely hold the parts in dustproof connection, and a central axially bored and interiorly threadedboss 8 is provided to secure the gong 9 by the use of a bolt 10.

The hammer 12 which in the operation strikes upon the interior surfaceof the gong, ispivotally mounted upon a lug 13 which projects inwardlyfrom the cylindrical wall of the casing in a plane with the outer edgeof the same.

The cover has a peripheral opening in which the lug snugly fits, and thelug has a circumferential flange 14 which engages the lower surface ofthe cover to effect a dust and moisture proof juncture.

While the lug may be formed integral with the wall of the casing, it isfor ease in manufacture, preferably made separately and secured in arecess in the wall by means of a screw 15.

It will be understood without further 'a straight bar 19 which ispivotally supported upon an inwardly projecting stud 20 on the plate 3to engage the poles of the magnet during its downward motion.

The hammer which as hereinbefore e-xpla1ned 1s plvotally mounted on the,lug 13,

. is by meansof a set screw secured upon the exterior end of a shortshaft 21 which is rotatably fittedin an opening in the lug and which atits inner end has a laterally projecting crank arm 22. V

A Wrist 23 projecting from the outer end of the crank arm, engages theouter edge of a lever 24 which at one of its extremities is movablysupported in axial alinement with the shaft 21 upon the reduced endportion of a'post 25 which is fixed on the back plate 3,. and whichextends loosely into a socket in the end of the shaft as shown in Fig.2.

The other extremity of the lever is by means of a link 26 connected withone of the ends'of the armature immediately below the same. A resilientabutment 27 which in the operation resists the return movement ofthechammer after it has struck the gong, consists of a cylindrical,exteriorly threaded barrel 28 which is longitudinally adjustably mountedin a correspondingly threaded opening of a post 29 secured upon the backplate of the housing. 7

A head formed at the end of the barrel, facilitates its adjustment, anda jam-nut 30 secured upon the barrel in engagement with the post,secures it in its adjusted positions.

Aplunger 31 slidably fitted in the barrel, projects beyond one endthereof to be'engaged by the end of the crank-arm on the hammer duringits return movement after it has struck the gong.

A stem of reduced diameter at the opposite end of the plunger projectsthrough an opening in the opposite end of the barrel,

a transverse pin 32 on the exterior portion of the'stemlimits theoutward movement of the plunger, and a spring 33 coiled around a portionofthe stem within the barrel, provides a cushion by resiliently opposingthe inward movement of the plunger when it is engaged by the crank arm.I

The circuit closing device of the apparatus consists of two contactmembers 35 and 1 34 one of which is fixed upon the back plate of thehousing in insulated relation thereto, and the other one of whichisadjustably mounted at the endof a pivoted arm 36 com- 1 posed ofnonconductive material.

The fixed contact member 35 consists of' a screw which is secured in anupright position in insulated relatlon to a bracket 37 on the plate "3,and the other, movable contact member, 34, is composed of an externallyThe plunger has a. threaded stem which loosely extends through anopening in the opposite endofthe barrel and which is proprojects beyondthe vided. with a pair of nuts 40 to limit the outward movement of theplunger when its lower end engages the fixed contact member.

A spring 41 coiled around the stem within the barrel deadens the impactbetween the contacts which at their engaging extremities are providedwith conductive tips of durable material, such as platinum or tungsten.

The end of the arm 36 in which its threaded opening is formed, is splitand a screw 42 projects through a threaded aperture transverse to theslit, for the purpose of clamping the contact member 3-l in its adjustedpositions. The arm is pivotally supported at its end opposite to that atwhich the contact member is secured, to move independently in thedirection of the movement of the armature, and for purposes ofconvenience and simplicity it is mounted upon the end of the same stud20 which supports the-armature. The armature and the arm are associatedfor synchronous operation during a part of the movement of the armature,by means of a pin 43 which extends laterally from the armature into anopening of greater diameter -14 in the arm, and a coiled spring 45 whichconnects the arm with the stationary bracket 37, and which serves toaccelerate the return movement of the movable contact member after ithas been separated from its fixed correlative.

The electrical connections of the alarm mechanism consist of a wire 46which connects the magnet windings with the contact member on thenonconductive arm 36, and two wires 47 and48 which respectively connectthe fixed contact member and the other end of the magnet winding withtwo binding posts 49 and 50 which are secured exteriorly of thecylindrical wall of the housing in insulated relation to the same.

The binding posts serve to connect the alarm mechanism in an electriccircuit which in Fig. 1 of the drawings has been shown in conventionalsymbols. the referspecific gravity and that of the member 34 as a wellas bythe action of the spring 45, maintains the contact members inengagement. The hammer is loosely suspended from the lug 13, and by theengagement of the wrist on its crank with the lower edge of the levermaintains the armature in its above described normal position. Now, whenby closing of the line circuit at 54, a current of electricity iscirculated through the coils of the magnet, the armature being quicklyattracted to the magnetized cores, causes the hammer to strike the gong.During the downward movement of the armature the two contact membersremain in engagement until the pin 43 engages the arm 36 at the upperend of its hole, which occurs before the armature has reached the magnetcores. The engagement of the pin with the arm causes the latter to movein synchronism with the armature, with the result that the contactmember 34: is separated from the fixed member and the circuit is consequently opened. As soon as the attractive power of the magnet isdiscontinued, the hammer returns by its specific gravity as well as byits recoil after having struck the gong, to its normal perpendicularposition, and in doing so engages the lever 24 with the result that thearmature which otherwise would have remained at rest on the magnetcores, is lifted to its normal position. The movement of the armaturepermits the con tact member 3 to reassume its normal position inengagement with the member 35 which again closes the circuit and therebyreenergizes the magnet. The consequent vibrative movement of thearmature is kept up as long as the circuit remains closed at 5 and thealarm is thus continuously sounded by the engagement of the hammer withthe gong at correspondingly regular intervals. The resilient abutment 27which is engaged by the crank arm on the hammer prior to the impact ofits wrist with the lever 2 L prevents violent contact of the members ofthe circuit-closing device, and at the same time renders the movement ofthe hammer equable. By adjustment of the position of the barrel of theabutment on the post 29, the movements of the hammer may be regulated tovary their frequency and in consequence that of the vibrative movementsof the armature, to any desired degree. The connection of the resilientcontact member 34L with the nonconductive arm 36 permits of itsadjustment for placing it in its proper position with relation to thefixed contact when the parts are assembled and for taking up wear of theconductive tips of the members.

It will be seen from the foregoing description that by maintaining themagnet circuit in a closed condition, until the armature approaches theend of its downward movement, the amount of current consumed in theoperation of the instrument is reduced to the minimum, that by theproper adjustment of the resilient abutment the frequency of the hammerstrokes may be varied to a degree which makes it possible to change theinstrument from a single stroke alarm to a vibrating alarm, that thesevariations in the operation of the instrument are produced solely byregulating the movement of the hammer which is mounted separately forindependent movement with relation to the armature, that the resiliencyof the movable contact member causes a wiping contact between the twomembers and prolongs the life of their engaging tips, and that theconstruction of the housing of the instrument efi ectively protects theoperating mechanism from dust and moisture without interfering with themovements of the hammer relative to the exteriorly disposed gong.

Having thus described my invention what I claim and desire to secure byLetters-Patent is:

1. In an electric alarm, an electro-magnet including an armature pivotedfor up and down movement, a lever connected to move with the armature, aloosely suspended, pivoted hammer, a crank-arm supporting said lever, incooperative connection with the hammer, and an adjustable abutmentrestricting the movement of the crank arm toward the lever.

2. In an electric alarm, an electro magnet including an armature pivotedfor up and down movement, a lever connected to move with the armature, aloosely suspended, pivoted hammer, a crank-arm supporting said lever, incooperative connection with the hammer, and a resilient, adjustableabutment restricting the movement of the crank arm toward the lever.

3. In an electric alarm, an electro-magnet including an armature pivotedfor up and down movement, a lever connected to move with the armature, aloosely suspended, pivoted hammer, a crank arm supporting said lever, incooperative connection with the hammer, and a resilient abutment torestrict the movement of the crank-arm toward the lever.

4. In an electric alarm, an electro-magnet including an armature pivotedfor upanddown movement, and a circuit-controlling device in themagnet-circuit, comprising a fixed contact-member, a rigid arm pivotedfor movement in the direction of the armature-movement, and aresilientcontact-member carried on the arm, adjustably in the direction of itsmovement with the same, the armature having means for separating themembers by engagement with said arm after it has passed through a partof its movement toward the magnet core.

5. In an electric alarm, an electro-magnet including an armature pivotedfor up-and down movement, and a circuit-controlling device in themagnet-circuit, comprising a fixed contact-member, a rigid arm pivotedfor movement in the direction of the armature-movement, a cylinderadjustably carried on the said arm, a contact-member ex tending movablyinto the cylinder, and a spring in the cylinder to yieldingly opposeinward movement of the movable contactanember, the armature having meansfor separating the 'mem'bers by engagement with said arm after 1t haspassed through a part of its movement toward the magnet core.

6; In an electric alarm,ran electro1nagnet including an armature pivotedfor upand-down movement, and a circuit-controlling device in themagnet-circuit, comprising a fixed contact-member, a rigidarm pivotedfor movement in the direction of the armature-movement, a cylindercarried on the Copies 01' this patent may be obtained for five centseach, by addressing the WILL C. NEAHR.

Two witnesses:

G. J. ROLLANDET, L. Rrroanns.

Commissioner of Paton,

Washington, D. G.

